Electronic cigarettes are electronic devices for delivering nicotine to the respiratory system by means of electronic heating, and it vaporizes a nicotine-containing solution to generate an aerosol. As compared with conventional cigarettes, the electronic cigarette has the following advantages: (a) the aerosol of the electronic cigarette does not contain harmful ingredients, such as tar, CO, and HCN; (b) the electronic cigarette vaporize a nicotine-containing solution (abbreviate as “e-liquid”) to generate an aerosol, and the aerosol can be quickly diluted in air, thereby no formation of second-hand smoke; (c) the use of the electronic cigarette does not involve a combustion process, and thus no cigarette ash and cigarette butt are produced, thereby to avoid potential danger of fire hazard. Such an electronic cigarette which combines modern microelectronic technique, biological technique, and healthy lifestyle concept together, can firmly grasp the mentality of consumers, and attract numerous consumers in a short time. At present, researches to the electronic cigarettes primarily focus on the design of electronic cigarette article, e-liquid and relevant accessories.
The aerosol mass is an important quality index for evaluating the performances of an electronic cigarette. The majority of smoke ingredients of conventional cigarettes is solid particles, and the minority of the smoke ingredients is liquid particles. Particles in the smoke have a large volume, and the aerosol mass of conventional cigarettes is usually measured by using a light scattering method, for example, see Chinese patent CN1113620C. The primary mechanism of the light scattering method is described as follows: a beam of light having a specific wavelength passes through smoke aerosol, the more solid particles in the smoke, the stronger scattering actions on light, whereby the transmission intensity of the light is lower; thus, the mass of the solid particles in the smoke can be measured quantitatively by measuring the transmission intensity of the light. However, the primary constituent of the electronic cigarette solution is liquid, such as propylene glycol, glycerol, nicotine, and flavor, and they are readily vaporizable upon heating to form small droplets which are dispersed in air, thereby to form an aerosol. The droplet particles not only have a smaller volume than solid particles, and more importantly, the droplets per se are transparent so that they do not have significant scattering actions on light as those of solid particles. Hence, when the light scattering method is used to measure the aerosol mass of electronic cigarettes, the corresponding scattering intensity and measuring precisions are low and the reproducibility is poor. Therefore, devices and methods for evaluating the aerosol mass of conventional cigarettes are not suitable for aerosol mass of electronic cigarettes. At present, the evaluations to the aerosol mass of electronic cigarettes are mainly based on human visual sensory evaluation, which can bring multiple subjective uncertainties. So far, the objective evaluation methods of the aerosol mass of electronic cigarettes have not been reported.